Any ideas on how to package the script to work on older versions of GLIBC?

Its easy, recompile PAR::Packer under older version of glibc, and then package your executable, and distribute that :) ( Re: Packaging Padre on Linux - nntp.perl.org , packaging-padre-on-linux )

Maybe you can recompile PAR::* with -static-libgcc, so it doesn't go looking for another one :)

Something else entirely :) http://cavapackager.com/